Integrally constructed parametric amplifier-circulator unit



Nov. 8, 1966 R. DAMIANO ET AL INTEGRALLY CONSTRUCTED PARAMETRIC AMPLIFIER-CIRCULATOR UNIT Filed Feb. 8, 1966 FIG.2

X'FORMER AMPLIFIER 2 AMPLIFIER X FORMER INVENTORS, ROBERT [mm/mo Ll PHU IS r A'T'FORNEYS United States Patent INTEGRALLY CONSTRUCTED PARAMETIRIC AMPLIFIER-CIRCULATOR UNIT Robert Damiano, St. James, and Jams Kliphuis, Huntington, N.Y., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Army Filed Feb. 8, 1966, Ser. No. 526,336

2 Claims. (Cl. 330-45) This invention relates to Y-junction circulators and more particularly, to cryogenically cooled Y-junetion circulators constructed as an integral part of a parametric amplifier.

One limiting factor in the development of cryogenically cooled parametric amplifiers has been the lack of suitable circulators and isolators. Ideally, these devices should provide a constant impedance, independent of operating temperature, because the gain stability of a parametric amplifier depends on the ratio of the negative impedance of the amplifier to the positive impedance presented by the circulator. Of course, low insertion loss and high isolation independent of operating temperature would also be provided by the ideal circulator.

We have invented a Y-junction multiple port circulator that provides a constant impedance, low insertion loss and high isolation independent of operating temperature. Our circulator is constructed as an integral part of the parametric amplifier. It has been found that type type of construction alfords the best possible stability and reliablity.

Accordingly, a primary object of our invention is to provide a multiple circulator constructed as an integral part of the amplifier.

Another object of our invention is to provide a cryogenically cooled Y-junction circulator for parametric amplifier applications.

A still further object of our invention is to provide a small size and lightweight Y-junction circulator in combination with a parametric amplifier.

The above and other objects of our invention will be apparent by reference to the following detailed description and accompanying drawing in which:

FIGURE 1 is a pictorial view of our invention; and

FIGURE 2 is a schematic representation of our invention.

The pictorial view of FIGURE 1 is given to show the small size and modular construction of our invention. As can be seen from the ruler in FIG. 1, the length of the circulator-amplifier module 12 is approximately 4% inches. To our knowledge no one has ever constructed a seven port circulator of such small size. It should also be pointed out that the circulator less the couplings weights only 0.4 of a pound.

The circulators 1, 2, 3, 4 and 5 are loaded with a polycrystalline yttrium iron garnet. Other suitable ferrites may also be used. Circulators 1, 3, and 5 are used as isolators. The parametric amplifiers 1 and 2 shown in FIG. 2 are located inside the waveguide couplers 13. The amplifiers are spring mounted to prevent damage from contraction and expansion of the housing. While any suitable type of parametric amplifier may be used, we prefer to use the amplifier described in US. Patent No. 3,105,941 granted to Jans Kliphuis, a coinventor of this invention, on October 1, 1963. This amplifier is ideally suited to our invention because of its small size, adaptability to modular construction and its operating characteristics.

Referring now to FIG. 2, input signals from any source such as an antenna 8 are coupled to circulator 1 by means of an input matching transformer 9. As was mentioned above circulators 1, 3 and 5 are used as isolators. All five circulators have arrows showing the direction of lCC signal travel through each circulator. Isolators 1, 3 and 5 yield a 40 db isolation between amplififier stages 1 and 2 and all other equipment and have a low insertion loss. We use circulators as isolators rather than conventional isolators because of the fact that the insertion loss of circulators is lower than the insertion loss of conventional isolators. The loads for the isolators are labelled 8 in the drawing.

The input signal is coupled to parametric amplifier 1 by means of circulators 1 and 2. The output of amplifier 1 is applied to the input of parametric amplifier 2 by means of circulators 2, 3 and 4, and the output of amplifier 2 is coupled to output terminal 11 by means of circulator 5 and the output matching transformer 10. The pump signals to the two amplifiers are applied at the terminals 6. The entire unit 12 is cooled by any suitable cryogenic refrigerator. Due to its configuration, unit 12 can be readily attached directly to the refrigerator bulkhead. This direct contact with the refrigerator minimizes heat loss.

Our invention may be utilized in any high frequency communications system and has been used successfully in a military satellite communications ground station. The military satellite communication band is 7.25 to 7175 go.

Our invention is ideally suited for use in this type of communications system and it has advantages not found in any like prior art devices. Some of these advantages are: (1) cool-down time is short due to the small mass; (2) heat load on the refrigerator is small because of the small structure required to support the cooled amplifier; and, (3) variation of circulator parameters with variations in temperature is small over a wide frequency range.

While we have described our invention with reference to a particular embodiment, it should be apparent to those skilled in the art that various modifications and changes can be made tothe disclosed embodiment without departing from the scope of the invention. For example, the seven port circulator disclosed can be reduced to a 5 or 3-port circulator without departing from the scope of the invention as disclosed with reference to the 7-port device. Therefore, it is our intention to be limited only by the scope of the appended claims.

We claim:

1. An integrally constructed cryogenically cooled parametric amplifier and circulator unit comprising: an irregularly shaped elongated housing; a first ferrite loaded isolator constructed in said housing; input signal means connected to said first isolator; a first parametric amplifier secured in said housing; a first ferrite loaded circulator constructed in said housing and connected between said first isolator and said amplifier; a second ferrite loaded isolator constructed in said housing and connected to said first circulator; a second parametric amplifier secured in said housing; a second ferrite loaded circulator constructed in said housing and connected between said sec ond parametric amplifier and said second isolator; signal output means; a third ferrite loaded isolator constructed in said housing and connected between said second circulator and said signal output means; and means to apply a pump signal to said first and second parametric amplifiers.

2. A parametric amplifier as described in claim 1 wherein said ferrite is yttrium iron garnet.

References Cited by the Examiner UNITED STATES PATENTS 3,040,267 6/1962 Seidel 330-4.9

ROY LAKE, Primary Examiner.

DARWIN R. HOSTETTER, Examiner. 

1. AN INTEGRALLY CONSTRUCTED CRYOGENICALLY COOLED PARAMETRIC AMPLIFIER AND CIRCULATOR UNIT COMPRISING: AN IRREGULARLY SHAPED ELONGATED HOUSING; A FIRST FERRITE LOADED ISOLATOR CONSTRUCTED IN SAID HOUSING; INPUT SIGNAL MEANS CONNECTED TO SAID FIRST ISOLATOR; A FIRST PARAMETRIC AMPLIFIER SECURED IN SAID HOUSING; A FIRST FERRITE LOADED CIRCULATOR CONSTRUCTED IN SAID HOUSING AND CONNECTED BETWEEN SAID FIRST ISOLATOR AND SAID AMPLIFIER; A SECOND FERRITE LOADED ISOLATOR CONSTRUCTED IN SAID HOUSING AND CONNECTED TO SAID FIRST CIRCULATOR; A SECOND PARAMETRIC AMPLIFIER SECURED IN SAID HOUSING; A SECOND FERRITE LOADED CIRCULATOR CONSTRUCTED IN SAID HOUSING AND CONNECTED BETWEEN SAID SECOND PARAMETRIC AMPLIFIER AND SAID SECOND ISOLATOR; SIGNAL OUTPUT MEANS; A THIRD FERRITE LOADED ISOLATOR; SIGNAL IN SAID HOUSING AND CONNECTED BETWEEN SAID SECOND CIRCULATOR AND SAID SIGNAL OUTPUT MEANS; AND MEANS TO APPLY A PUMP SIGNAL TO SAID FIRST AND SECOND PARAMETRIC AMPLIFIERS. 